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One fifth of humanity deprived of Milky Way

None more black light

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One-fifth of the world's population is deprived of the pleasure of viewing the Milky Way in all its splendour - thanks, you guessed it, to light pollution.

However, this for once is not a case of developing world citizens yet again being sold short, because the light-out specifically affects "two thirds of the US population and one half of the European Union population", with Blighty figuring large among the total 20 per cent worldwide who are sine Via Lactea.

That's according to Connie Walker, an astronomer from the US National Optical Astronomy Observatory in Tucson, Arizona, who used figures from various sources including the public-participation Globe at Night project to arrive at her conclusion.

She lamented: "The arc of the Milky Way seen from a truly dark location is part of our planet's natural heritage."

To give an idea of the scale of the problem, Walker specifically found that "cities using light fixtures that direct just 3 per cent of their light upwards can almost double the sky glow experienced by astronomical observatories 100 km away".

She elaborated: "Allowing 10 per cent direct uplight increases this figure to 570 per cent."

Walker is chair of the US Dark Skies Working Group, part of the Dark Skies Awareness program, described by Cosmos Online as "a global citizen science effort to raise awareness of light pollution".

She said: "The point of raising awareness of light pollution is that it touches many areas of people's lives, from simply not being able to see the natural heritage of a starry night sky to affecting... the habits of animals, energy consumption, economic resources, and astronomical research."

In case you're thinking that light pollution is nothing more than an inconvenience for astronomers and city-bound skygazers, Walker cited a 2008 study of 147 Israeli communities, published in journal Chronobiology International, which "found some evidence for an increased risk of breast cancer for women living in areas with the most light pollution".

This was believed to be linked to "unnatural light at night affecting levels of hormones such as melatonin and estrogen". ®